seems that this line of printers has latent static issues. i've helped a couple of people get there sp's and vp's going and it was many times static charge.
in the future, to completely disperse of all static charge in the machine do this in this order. you won't need to leave the machine off for 10 minutes or over night.
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turn it off from the front, turn it off from the back, unplug the back, press the front power button four times slowly (press count to 2, press count to 2, etc). this eliminates all the charge from the machine. some main boards have capacitors that are designed to store electricity. by pressing the front power you pull power out of the machine. my mimaki's front button will light up green about 2 times before going dark, unplugged, to show you when the static charge is gone.
also, anytime you get gibberish (especially long or short bars of a single color), that is a sign of a data issue, long streaks that end intermittently is usually a fried print head. my printer was very periodically printing little 1x2 rectangles for weeks before it nuts. the diagnosis was a loose data ribbon at the black head. so that's a heads up if you see that kind of issue. check for ink leaks into ribbon inlets, loose data cables, and bent over data cable leads). when checking completely power down your machine as if you were changing a head.